1. Field of the Invention
This invention relates generally to locking devices, and is more particularly directed to a removable locking apparatus for use in preventing or limiting the sliding movement of a metal type window or the like.
2. Description of the Prior Art
It is well known in the art that many problems and difficulties are encountered in providing suitable means for limiting and/or preventing the lateral sliding movement of panels and closures, especially with sliding metal casement windows where each window is movably supported within channel-like frame sections which form a generally rectangular casement frame structure wherein the upper and lower frame sections are formed as tracks to slidably receive the window section therein.
Several types of locking devices have been tried but with limited success, due to various inherent problems of the particular arrangement of each specific locking device.
For example, U.S. Pat. No. 3,428,349 discloses a channel-shaped body member which is mountable on a window or door-guide flange in position to be engaged by the closure, the channel-shaped body being secured to the flange by a thumb screw mounted on one of the body flanges. Thus, if one does not provide enough strength to turn the thumb screw in a very tight bind against the window-guide flange, the window can be moved against the channel body with a force to overcome the binding force applied by the thumb screw. Thus, one would need an additional tool to turn the thumb screw for a positive locking engagement.
In U.S. Pat. No. 3,415,560 there is disclosed a locking device comprising a housing defining a passage having a ball disposed in the passage. When the device is installed, a spring urges the ball towards a surface of the window structure; and thus the ball becomes wedged in the passage against the window structure. However, if the window is slightly ajar, leverage can be applied directly or intermittently, causing the ball to slip within the passage.
A further example is disclosed in U.S. Pat. No. 3,975,041 which provides a clamping-wedge member for wedging against the corner of the sliding panel.
Another type of lock for sliding windows and doors is disclosed in U.S. Pat. No. 3,490,802 which provides a stop block having a lock pin extending from the block to engage a sliding panel.